Methods for suppressing flame

ABSTRACT

The invention relates to flame suppression compositions including an inorganic halogen-containing component including bromine, iodine, or a mixture thereof, and an organic binder system having a heat of formation of less than about 200 cal/g, wherein the composition is solid at a temperature below 100° C. and combusts at a temperature between about 160° C. to 1200° C. to produce a plurality of reaction products capable of suppressing a flame upon application thereto and wherein substantially all the halogen is converted to a solid form after suppressing the flame. The invention also relates to methods of suppressing flames by combining an inorganic halogen-containing component including bromine, iodine, or a mixture thereof, with an organic binder system having a heat of formation of less than about 200 cal/g to form a solid composition, generating a plurality of reaction products from the composition in a substantially gaseous form, wherein the reaction products have a velocity, and applying the reaction products at a temperature of between about 160° C. to 1200° C. to at least one flame in an amount sufficient to suppress the flame, wherein substantially all the halogen is solid after suppressing the flame.

This is a division of application Ser. No. 08/968,588, filed Nov. 13,1997, now U.S. Pat. No. 5,861,106.

TECHNICAL FIELD

This invention relates to flame suppression compositions including aninorganic halogen-containing component including bromine, iodine, ormixtures thereof, and an organic binder system. Also disclosed aremethods of suppressing flames by combining compositions including aninorganic halogen-containing component and an organic binder system,generating a gas by combusting a composition and applying the productsthereof to at least one flame at a temperature of between about 160° C.to 1200° C. in an amount sufficient to suppress the flame.

BACKGROUND OF THE INVENTION

Flame suppression is typically achieved with the use of both physicaland chemical mechanisms. As used herein, "flame suppression" or"suppression" include inhibiting, suppressing, or extinguishing flames.The physical mechanism involves heat absorption by the molecules of aflame extinguishing composition sufficient to lower the temperature ofthe combusting materials below the ignition point or alternatively bydisplacement of oxygen, either of which will terminate combustion.Generally, as the extinguishment molecule increases in size (the moreatoms and bonds it contains) so do the degrees of vibrational freedom,thus the higher the vapor heat capacity and the greater the heatremoval. The chemical mechanism involves interruption of the radicalflame-propagation chain reactions, which are the various reactions ofhydrogen, oxygen, and hydroxyl radicals that produce flame. It has beenspeculated that bromine atoms disrupt these chain reactions, which alsotypically terminates combustion. Halides are ranked for their flamesuppression capabilities. Fluorine/fluorides are assigned a value of 1,while the value is 5 for chlorides, 10 for bromides, and 16 for iodides,i.e., iodides are 16 times more effective than fluorine/fluorides.

A variety of agents and techniques are currently used for flamesuppression, which use either chemical or physical action, or both, toachieve flame suppression. One conventional agent is a pressurized waterextinguisher model that functions solely by thermal energy absorption.Such models are not suitable, however, for use on electrical orflammable-liquid fires. Carbon dioxide (CO₂) and dry-chemicalextinguishers are in use and typically displace oxygen and absorbthermal energy, although dry-chemicals typically leave a corrosiveresidue. Even better for use against grease fires are sodium bicarbonateextinguishers, as well as potassium bicarbonate, urea-based potassiumbicarbonate, and potassium chloride extinguishers, although the lattertypes leave a heavy powdered chemical residue that can damage electricalequipment. Yet another conventional fire extinguisher is the foam (AFFFor FFFP) model, which coats flammable liquids with a chemical to lowerthe temperature or eliminate oxygen supply, although these are notsuitable for electrical fires [Nat'l Fire Protection Ass'n, 1995].

U.S. Army studies on halogenated agents in the 1940's resulted in theadoption of the well known HALON family of flame suppressioncompositions. HALONS, although environmentally deleterious, arecurrently in use as highly effective fire suppressionagents--particularly in tanks, planes, ships, and heavy engines.Conventional halogenated agents, such as carbon tetrachloride andHALONS, e.g., bromotrifluoromethane, tend to employ both physical andchemical flame suppression mechanisms.

The HALONS are bromofluorocarbons ("BFCs") that are similar tochlorofluorocarbons ("CFCs") but have the formula C_(w) Br_(x) Cl_(y)F_(z) (where W=1 or 2, Y=0 or 1, and X+Y+Z=2W+2). HALONS must besufficiently heated and pyrolyzed by a flame to produce free radicalsbefore they achieve sufficient firefighting efficacy. Thus, HALONS arefairly stable and tend to work best on fires with hotter flametemperatures. This stability results in only a 5% effectivity forHALONS. As a result, these organic compounds tend to have longatmospheric lifetimes and migrate to the stratosphere where they undergophotolysis when struck by ultraviolet radiation, thereafter typicallydecomposing to give chlorine or bromine radicals that act tocatalytically destroy the protective ozone layer of the earth, as wellas possibly adding to global warming. This depletion of stratosphericozone allows more ultraviolet light to reach the surface of the earth,resulting in increases in human skin cancer and cataracts, as well asdamage to crops, natural ecosystems, and materials and various otheradverse effects. Chlorine- and bromine-containing haloalkanes are knownto deplete stratospheric ozone, with bromine posing a greater problem(per atom) than chlorine. Indeed, conventional brominated agents andother volatile halogenated alkenes are presently being eliminated fromworldwide production, pursuant to the adoption of the Montreal Protocoland the Clean Air Act of 1990, due to their tremendous potential todestroy the stratospheric ozone layer.

The costs of perfluorocarbons are higher, and their firefightingperformance is less effective, than those of the brominated agents. Inweight and volume critical situations, such as aircraft, tanks, andships, the additional quantity required for extinguishment isunacceptable. Perfluorinated agents have high global warming potential("GWP") and atmospheric lifetimes estimated to be several thousandyears. Moreover, their production and use is also being restricted bypending legislation and liability concerns of current manufacturers.

In order to quantify these concerns, halogen-containing flamesuppression agents are assigned an ozone-depletion potential ("ODP")that reflects their quantitative ability to destroy stratospheric ozone.The ozone depletion potential is calculated in each case relative toCFC-11 (CFCl₃, trichlorofluoromethane), which has been assigned a valueof 1.0. Many CFCs have ODPs near 1; HALONS have higher ODPs between 2and 14, indicating a greater ozone depletion potential. There is thus aneed for firefighting, or flame suppression, compositions that overcomethe drawbacks of conventional agents as discussed above.

Firefighting compositions to replace HALONS should be effectiveextinguishants, relatively nontoxic, electrically nonconductive,evaporate cleanly, and have low or no environmental impact. HALONS,although they meet the first four criteria, have long atmosphericlifetimes and high ozone-depletion potentials, and are being phased outof use as discussed above.

Although it is relatively easy to identify fire suppressing agentshaving one, two, or three of these properties, it is very difficult toidentify chemicals that simultaneously possess effective firesuppression performance, non-flammability, low toxicity, cleanliness,electrical non-conductivity, miscibility with common lubricants, shortatmosphere and environmental lifetimes, low or no ODP, and very low GWP.Other characteristics are desirable, such as reduced toxicity, which isanother major issue in the selection of firefighting agents. Forexample, the toxic effects of haloalkenes includes simulation orsuppression of the central nervous system, initiation of cardiacarrhythmias, and sensitization of the heart to adrenaline. Inhalation ofgaseous haloalkanes can cause bronchoconstriction, reduce pulmonarycompliance, depress respiratory volume, reduce mean arterial bloodpressure, and produce tachycardia. Long term effects can includehepatotoxicity, mutagenesis, teratogenesis, and carcinogenicity.

Furthermore, firefighting agents must also be chemically stable duringstorage and use over long periods of time, and must be unreactive withthe containment system in which they are housed. Firefighting agentsmust typically be stable on storage at temperatures of about -20° C. to50° C., and should decompose at flame temperatures to yieldradical-trapping species.

A variety of alternative agents containing halides are known for firesuppression, although they are either less effective than HALONS or lackone of the characteristics desired in flame suppression agents asdescribed above. Some of these methods and agents are discussed below.For example, one neat iodinated agent (trifluoroiodomethane, CF₃ I) haslong been known to have firefighting potential [Dictionary of OrganicCompounds, Chapman and Hall, New York, p. 5477 (1982)].

U.S. Pat. No. 2,136,963 discloses a fire extinguishing agent and methodthat covers burning material with foam produced by a mixture of a liquidand a compound selected from high molecular quaternary ammonium,phosphonium, and sulphonium compounds. These compounds are disclosed toinclude a variety of bromides and iodides.

U.S. Pat. No. 2,818,381 discloses methyl bromide used for extinguishingfires. This reference also discloses another early fire extinguishingcomposition having 10-40 parts by weight of a chloro-difluoro methanehaving between one and two chlorine atoms, with 90-60 parts by weight ofa mixture of bromoform and ethyl bromide.

U.S. Pat. No. 3,779,825 discloses a solid propellant composition having60 to 90 weight percent oxidizer component selected from solid inorganicoxidizing salts of ammonium perchlorate, the alkali metal perchlorates,ammonium nitrate, the alkali metal nitrates, and mixtures thereof, atleast a major portion of the oxidizer being of the perchlorates; from 10to 40 weight percent of a binder of a rubbery material; and from 0.1 to8 weight percent of a burning rate depressing agent.

U.S. Pat. No. 4,406,797 discloses a fire extinguishing compositionhaving a mixture of finely divided aluminum compound and an alkalimetal, stannous or plumbous halide. The metal halide may include analkali metal, e.g., potassium iodide, bromide, or chloride, or stannousor plumbous iodide, bromide or chloride, although potassium iodide isdisclosed to be preferred for use in the composition.

U.S. Pat. Nos. 4,486,317 and 4,380,482 disclose methods for preparingand compositions of a thickener in aqueous solution or slurry stabilizedagainst thermal degradation by inclusion of any of a variety of suitableiodide and/or iodate ions in the solution or slurry. The method andcomposition also include a thermally stabilizing amount of iodide ionselected from hydriodic acid, ammonium iodide, an alkyl-substitutedammonium iodide, or an alkali metal or alkaline-earth metal iodide,iodate ion selected from iodic acid, ammonium iodate, analkyl-substituted ammonium iodate, or an alkali metal or alkaline-earthmetal iodate, or a combination of the iodide and iodate ion compound.The iodate ion is disclosed as effective in amounts up to about 0.6%,although an iodate concentration up to 0.3% is preferred, as higherconcentrations result in conversion of iodate to iodide over time andhigh temperature.

U.S. Pat. Nos. 4,961,865 and 4,950,410 disclose methods and compositionsfor inhibiting the combustion of wood and other cellulosic materials byimpregnating such material with compositions including a mixture ofsodium chloride, magnesium chloride, sodium sulfate, sodium borate,calcium chloride, magnesium sulfate, and water. The composition may alsooptionally include calcium sulfate, potassium sulfate, calcium chloride,magnesium sulfate, magnesium bromide, and potassium chloride.

U.S. Pat. No. 5,466,386 discloses fire-extinguishing compositions of lowozone depletion potential having dry particles of ammonium bromidecoated with a water repelling, solid, non-flammable adherent, such aszinc stearate, to improve flowability. The particles allegedly enhancethe fire-extinguishing properties of chlorofluorocarbons and halogenatedparaffins having low ozone depletion properties when dispersed therein.

U.S. Pat. No. 5,520,826 discloses a flame extinguishing pyrotechnichaving an azido binder, such as a glycidyl azide polymer (GAP), an azidoplasticizer, a solid tetrazole, and a perfluorocarboxylic acid saltcured to a rubbery composite by the addition of an isocyanate thatflamelessly deflagrates to produce primarily nitrogen, carbon dioxide,and a fluoroolefin.

U.S. Pat. No. 5,562,861 discloses a set of environmentally safe,nonflammable, low-toxicity refrigerants, solvents, foam blowing agents,propellants, and firefighting agents that allegedly have noozone-depletion potential. These agents include at least onefluoroiodocarbon agent of the formula C_(a) H_(b) Br_(c) Cl_(d) F_(e)I_(f) N_(g) O_(h), where a is 1 to 8; b is 0 to 2; c, d, g, and h areeach 0 to 1; e is 1 to 18; and f is 1 to 2. This reference also notesthat conventional chemical wisdom indicates that iodine-containingorganic compounds are too toxic and unstable to use for these purposes,and iodocarbons have been rejected on those grounds by the majority ofthose skilled in the art.

U.S. Pat. No. 5,626,786 discloses a class of fire suppressant compoundshaving labile bromine atoms bound to non-carbon atoms that are allegedto be more effective than HALON 1211 and 1301 at suppressing fires.These compounds are disclosed to hydrolyze or oxidize rapidly in thetroposphere, thereby having minimal ODP.

Reduction of toxicity, ODP, and other environmental effects must bebalanced against effective flame suppression to achieve a superior flamesuppression composition and method. Although more recent conventionalflame suppression compositions have achieved limited ozone depletionpotential, it is typically at the expense of fire suppressioneffectiveness or volume efficiency. Thus, the need exists for anenvironmentally-friendly, non-toxic fire suppression composition, anduse thereof, that have better fire suppression effectiveness thanHALON-type agents.

SUMMARY OF THE INVENTION

The invention relates to flame suppression compositions having aninorganic halogen-containing component including bromine, iodine, or amixture thereof, and an organic binder system having a heat of formationof less than about 200 cal/g, wherein the composition is solid at atemperature below 100° C. when cured and combusts at a temperaturebetween about 160° C. to 1200° C. to produce a plurality of reactionproducts capable of suppressing a flame upon application thereto. Thereaction products are affected by the flames, thereby convertingsubstantially all of the halogen into a solid form after suppressing theflame.

In a preferred embodiment, the inorganic halogen-containing componentincludes potassium bromide, potassium bromate, potassium iodide,potassium iodate, ammonium bromide, ammonium bromate, ammonium iodide,or ammonium iodate, or a mixture thereof. In a more preferredembodiment, the inorganic halogen-containing component is selected fromthe group of potassium iodate, potassium bromate, potassium bromide,ammonium iodate, and a mixture thereof. In a preferred embodiment, theorganic binder system of the composition includes a binder resin of atleast one curing binder, melt cast binder, solvated binder, or a mixturethereof, a curative present in about 1 to 3 weight percent, and aplasticizer present in about 10 to 30 weight percent, wherein theorganic binder system has a heat of formation of less than about 0cal/g. In a preferred embodiment, the organic binder system furtherincludes at least one of a curing or bonding agent, an antioxidant, anopacifier, or a scavenger. In another preferred embodiment, the binderresin is carboxy-terminated polybutadiene, polyethylene glycol,polypropylene glycol, hydroxy-terminated polybutadiene, polybutadieneacrylonitrile, polybutadiene acrylic acid, butacene, glycol azidoadipate, polyglycol adipate, or a mixture thereof.

In a preferred embodiment, the organic binder system is present in anamount of about 4 to 15 weight percent of the composition. In a morepreferred embodiment, the organic binder system is present in an amountof about 8 to 12 weight percent of the composition.

In one embodiment, the reaction products of the composition include H₂O, CO, and a halogen-containing byproduct of the group selected from KI,KBr, I₂ OH, K₂ I, and a mixture thereof. In another embodiment, thereaction products are in a substantially gaseous state prior toapplication to the flame.

The invention also relates to methods of suppressing flames by combiningan inorganic halogen-containing component having bromine, iodine, or amixture thereof, and an organic binder system having a heat of formationof less than about 200 cal/g to form a solid composition, generating aplurality of reaction products from the composition in a substantiallygaseous form, wherein the reaction products have a velocity, andapplying the reaction products at a temperature of between about 160° C.to 1200° C. to at least one flame in an amount sufficient to suppressthe flame, wherein substantially all the halogen is solid aftersuppressing the flame.

In one embodiment, the gaseous reaction products are generated bycombusting the composition at a temperature of about 160° C. to 1200° C.prior to application to the at least one flame. In another embodiment,the velocity of the gaseous reaction products generated from thecomposition is reduced to facilitate directing or channeling of thereaction products into the flame. In a preferred embodiment, theinorganic halogen-containing component is selected to include potassiumbromide, potassium bromate, potassium iodide, potassium iodate, ammoniumbromide, ammonium bromate, ammonium iodide, or ammonium iodate, or amixture thereof. In a more preferred embodiment, the inorganichalogen-containing component is selected from the group of potassiumiodate, potassium bromate, potassium bromide, ammonium iodate, and amixture thereof.

In another embodiment, the organic binder system is prepared bycombining a binder resin of at least one curing binder, melt castbinder, solvated binder, or a mixture thereof, a curative present inabout 1 to 3 weight percent, and a plasticizer present in about 10 to 30weight percent, wherein the organic binder system has a heat offormation of less than about 0 cal/g. In a preferred embodiment, theorganic binder system is selected to further include at least one of acuring or bonding agent, an antioxidant, an opacifier, or a scavenger.In another preferred embodiment, the binder resin is selected to includecarboxy-terminated polybutadiene, polyethylene glycol, polypropyleneglycol, hydroxy-terminated polybutadiene, polybutadiene acrylonitrile,polybutadiene acrylic acid, butacene, glycol azido adipate, polyglycoladipate, or a mixture thereof.

In another embodiment, the reaction products are applied in an amountsufficient to extinguish the flame. In another embodiment, the reactionproducts generated are selected to include H₂ O, CO, and ahalogen-containing byproduct of the group selected from KI, KBr, I₂ OH,K₂ I, and a mixture thereof.

BRIEF DESCRIPTION OF THE DRAWING

The present invention may be more clearly understood by reference to thefollowing FIGS.

FIG. 1 illustrates a device used to reduce the velocity and direct thereaction products of the composition into a flame according to thepresent invention.

FIG. 1A illustrates an end view of one end of the device of FIG. 1according to the present invention.

FIG. 2 illustrates a flow diagram of a flame and the insertion andeffect of the reaction products of the flame suppression composition ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention avoids the environmentally adverse effects ofHALONS and other flame suppressing agents by providing environmentallysafe, highly effective flame suppressing compositions that are alsoclean, electrically nonconductive, minimally toxic at worst,nonflammable (self-extinguishable), and have short atmospheric lifetime.The present invention accomplishes this with a flame suppressioncomposition including a combination of an inorganic halogen-containingcomponent and a binder system, which is typically organic in nature, ina solid form at a temperature below 100° C. when cured, and capable ofcombusting at a temperature between about 160° C. to 1200° C. to producea plurality of reaction products for application to flames and whereinsubstantially all the halogen is in a solid form after suppressing theflame. The present invention also includes a method of suppressingflames by combining an inorganic halogen-containing component includingbromine, iodine, or a mixture thereof, and an organic binder systemhaving a heat of formation of less than about 200 cal/g to form a solidcomposition and subsequently generating a plurality of reaction productsfrom the composition in a substantially gaseous form, and applying thereaction products at a temperature of between about 160° C. to 1200° C.to flames in an amount sufficient to suppress the flames, wherein thereaction products are converted by the flame or combustion so thatsubstantially all the halogen is in a solid form. Typically, thereaction products are generated from the composition by combustion inthe presence of oxygen, although other types of combustion may be usedto generate the reaction products.

The inorganic halogen-containing component of the present invention istypically an alkali halide, which may either be an oxidizer or an inertsource of halogen species. The component is preferably potassium orammonium compounded with bromide, bromate, iodide, or iodate. Morepreferably, the inorganic halogen-containing component contains iodideor iodate, and most preferably the inorganic halogen-containingcomponent contains at least 50 weight percent potassium iodate. Theiodates and bromates, which form oxidizers, are dense materials thattypically form free liquid prior to curing with the organic bindersystem. The iodides and bromides, such as potassium iodide or potassiumbromide, are sources of halogen species that are not oxidizers.

Propellants, including potassium bromate, tend to accelerate combustion.Accelerants, which may be desirably used under certain situations,facilitate more rapid gas generation and administration of thecomposition to flames. Thus, potassium bromate is typically only used inless than about 35 weight percent of the composition. Larger amounts ofpotassium bromate in the composition tend to cause rapid combustion thatrenders the composition less effective as a flame suppressant. Potassiumor ammonium iodate, however, combust relatively slowly. An increase inthe combusting of the iodates may be accomplished by also including acombustion accelerant, such as potassium bromate, in the composition.Measurement of the combustion rate and optimization thereof are readilyunderstood by those of ordinary skill in the art.

The binder system used in the composition is typically organic andincludes at least a binder, or binder resin, and a plasticizer. Thebinder resin includes at least one of a curing binder, melt cast binder,or solvated binder, or a mixture thereof. The binder system may alsoinclude one or more of a curing or bonding agent, an antioxidant, anopacifier, or a scavenger, such as lithium carbonate.

Curing agents suitable for use with the invention may includehexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI),toluene diisocyanate (TDI), trimethylxylene diisocyanate (TMDI), dimeryldiisocyanate (DDI), diphenylmethane diisocyanate (MDI), naphthalenediisocyanate (NDI), dianisidine diisocyanate (DADI), phenylenediisocyanate (PDI), xylene diisocyanate (MXDI), other diisocyanates,triisocyanates, higher isocyanates than the triisocyanates,polyfunctional isocyanates, or a mixture thereof. The amount of thecuring agent needed is generally determined by the desired stoichiometrybetween the curable binder and the curing agent. The curing agent istypically present in an amount of up to about 5%. However, if a curablebinder is used, the curing agent is present from about 0.5% to about 5%.

When a curing agent is used, a cure catalyst is preferably included toaccelerate the curing reaction between the curable binder and the curingagent. Suitable cure catalysts may include alkyl tin dilaurate, metalacetylacetonate, triphenyl bismuth, maleic anhydride, magnesium oxide ora mixture thereof. A preferred cure catalyst is an equal percent byweight mixture of each of triphenyl bismuth, maleic anhydride andmagnesium oxide. The cure catalyst, when used, is generally present fromabout 0.1 to 0.3% by weight.

An opacifier may be used in the binder system, generally in an amountfrom about 0.01% to 2% by weight. One suitable opacifier is carbonblack.

Antioxidants may also be used in the invention. Suitable antioxidantsmay include 2,2'-bis(4-methyl-6-tert-butylphenol),4,4'-bis(4-methyl-6-tert-butylphenol) or a mixture thereof. Theantioxidant is typically present in an amount of up about 0.1 to 1% byweight.

Whether or not these additives are included, the binder system as awhole typically has a heat of formation of less than about 200 cal/g,preferably a negative heat of formation, more preferably a heat offormation of less than about -200 cal/g, and most preferably less thanabout -400 cal/g. Binder systems with low heats of formation aredesired, as they facilitate flame suppression by absorbing more heatfrom the flame and they also have higher thermal stability to providefor long-term storage. Binders having a lower heat of formation whencombusted with a propellant are thus preferred, as they tend to producelower flame temperatures. The binder systems preferred also tend to bechemically stable, such that they will not react with the inorganichalogen-containing component prior to use as a flame suppressant. Thebinder chosen for the binder system may include any such resin having alow flame temperature and heat of formation. Several preferred bindersinclude, for example, carboxy-terminated polybutadiene (CTPB),polyethylene glycol (PEG), polypropylene glycol (PPG),hydroxy-terminated polybutadiene (HTPB), polybutadiene acrylonitrile(PBAN), polybutadiene acrylic acid (PBAA), butacene (HTPB iron adduct),glycol azido adipate (GAP), polyglycol adipate (PGA), or a compatiblemixture thereof. Nitrous cellulose and nitroglycerin are two binderresins that are undesirable for use in a binder system of the presentinvention, as they tend to be chemically and thermally unstable and thusunsuitable for use in fire suppression compositions. The determinationof the appropriate binder type and other binder system components, andamounts suitable for use therewith, will be readily understood by one ofordinary skill in the art when selected according to the teachingsherein.

The binder system may include a curative, typically present in about 1to 3 weight percent of the organic binder system, and generally includesa plasticizer, typically present in about 10 to 30 weight percent of theorganic binder system. The heats of formation for the curative andplasticizer must also be factored into the heat of formation of thebinder system when they are included. Any plasticizer with a suitablylow heat of formation may be used, such as triacetin or di-octyl adipate(DOA). The curative must be similarly selected, such as isophoronediisocyanate (IPDI). The heats of formation of several preferredbinders, curatives, and plasticizers are shown in Table I below.

                  TABLE I                                                         ______________________________________                                        Approximate Heat of Formation of Binder System Components                     Material      Heat of Formation (cal/g)                                                                       Function                                      ______________________________________                                        BAMMO/AMMO    240               Binder                                        carboxy-terminated                                                                          -16               Binder                                        polybutadiene (CTPB)                                                          polyethylene glycol (PEG)                                                                   -1,060            Binder                                        polypropylene glycol (PPG)                                                                  -1,090            Binder                                        hydroxy-terminated                                                                          -16 to +30 (sources vary)                                                                       Binder                                        polybutadiene (HTPB)                                                          polybutadiene acrylonitrile                                                                 160               Binder                                        (PBAN)                                                                        polybutadiene acrylic acid                                                                  -84               Binder                                        (PBAA)                                                                        butacene (HTPB iron                                                                         -100              Binder                                        adduct)                                                                       glycol azido adipate (GAP)                                                                  340               Binder                                        polyglycol adipate (PGA)                                                                    -1,200            Binder                                        Triacetin     -1,300            Plasticizer                                   di-octyl adipate (DOA)                                                                      -730              Plasticizer                                   isophorone diisocyanate                                                                     -500              Curative                                      (IPDI)                                                                        ______________________________________                                    

A more preferred binder system includes PGA or HTPB with a triacetinplasticizer. The PGA/triacetin combination, for example, has a combinedheat of formation of -2,500 cal/g. The combination of the inorganichalogen-containing component and the organic binder system typicallyproduces a rubbery-like solid material that can be combusted to formreaction products capable of suppressing flames.

The flame suppressing compositions, when used in the methods of theinvention, are combusted at temperatures between about 160° C. to 1200°C., preferably about 300° C. to 1100° C., to produce an effluent ofprimarily gaseous reaction products. These reaction products typicallycontain H₂ O, CO, and a halogen-containing byproduct of the groupselected from KI, KBr, I₂ OH, K₂ I, and a mixture thereof. Thesereaction products are applied to flames as discussed below to suppressthe flames according to the present invention. The type of halogen foundin the halogen-containing byproduct depends upon the inorganichalogen-containing component present in the flame suppressioncomposition.

The gaseous reaction products typically travel at a sonic velocity orfaster when exiting the area where the flame suppression compositionsare combusted. In a preferred embodiment, the velocity of the gaseousreaction products is reduced to facilitate directing the effluent to adesired location in the flames. For example, a conventional nozzle,duct, or shock tube may be readily selected as desired by those ofordinary skill in the art to reduce the velocity of the gas and tofacilitate the direction of the gas into the flame to be suppressed. Oneexample of a conventional subsonic nozzle/shock shock tube device isillustrated in FIG. 1, along with the relative dimensions thereof. Athroat 2 having a diameter D permits the combusted composition in theform of the reaction products to flow from the shock tube 5. Shock tubes5 typically contain a liner 8 of a silica or phenolic composition and ashell 10 of metal. Various conventional dimensions of the shock tube 5are described as multiples of the diameter D. For example, the length ofthe entire shock tube 5 is 34D, or 34 times the diameter D of the throat2. FIG. 1A illustrates an end view of the device in FIG. 1 from the endwhere the throat 2 is located. Typically, the invention uses one or moredevices to store the composition, to contain the combusting composition,in a preferred embodiment to reduce the velocity of the reactionproducts to facilitate directing the reaction product effluent, and in apreferred embodiment to facilitate direction of the effluent to theflame. One of ordinary skill in the art with knowledge of these devicesis readily able to select a suitable device for use with the presentinvention.

When the flame suppression composition is combusted to form theplurality of reaction products, the reaction products are in a primarilygaseous form. The reaction products are applied to the flame as withconventional flame suppression agents, i.e., typically near the bottomof the flame. The reaction products of the invention typically enter theflame at a temperature of between about 160° C. to 1200° C. Withoutwishing to be bound by any particular theory, it is believed that thereaction products link with oxygen to block the flow of oxygen into theportion of the flame. Flames are believed to involve a combination oftwo reactions: (1) an endothermic reaction that produces free radicalsfrom a fuel; and (2) an exothermic reaction that provides heat to theendothermic reaction, where the exothermic reaction is produced by thereaction of free radicals with oxygen. By providing free radicals in theform of low or negative heat of formation reaction products, the presentinvention is believed to suppress the exothermic reaction that permitsthe fuel's free radicals and oxygen to react. The combination of thereaction products of the present invention with oxygen or othercomponents required for the flame results in a slightly exothermic orendothermic reaction. Absent the heat of the typical exothermicreaction, endothermic production of free radicals from the fuel isreduced and results in a slowing or halt of the reactions and conditionsrequired to maintain a flame. If enough of the reaction products of thepresent invention are applied to the flame, the flame is suppressed andeventually extinguished. The discussion above is not intended torestrict the invention to a particular embodiment or narrow theinterpretation of any terms herein.

FIG. 2 illustrates a sample flow diagram of the reactions believed tooccur in a flame 15. There are generally two zones in a flame 15, Zone A18 and Zone B 20. Zone A 18 is generally where the endothermic reactionoccurs that splits free radicals from the fuel. Zone B 20 is generallywhere the exothermic reaction occurs that combines the free radicals andoxygen. The heat radiating downward from Zone B 20 to Zone A 18 helpssplit more free radicals in the endothermic reaction. It is believedthat the radicals in the reaction products 23 of the present inventioncombine with oxygen 25 and inhibiting reaction 28 of the conventionalradicals 35 and oxygen 25. Normally, the oxygen 30 would be freelyavailable for bonding with the free radicals 35 to produce aconventional combustion reaction 32. Thus, FIG. 2 illustrates how thecompositions and method of the present invention suppresses orextinguishes flame.

Following suppression or extinguishment of the flame, substantially allof the halogen in the reaction products is converted into ahalogen-containing byproduct that preferably becomes solid as it leavesthe vicinity of the flame. This solidification is believed to occur asthe reaction products leave the flame and cool, thereby vastlydecreasing the toxicity and ozone depletion potential of the halogen inthe halogen-containing byproduct by ensuring solidification.

"Substantially all" of the component is defined herein to mean at leastabout 90 weight percent, preferably at least about 95 weight percent,and more preferably at least about 99 weight percent of the flamesuppression composition. The "flame suppression composition(s)" of thepresent inventions are defined to include compositions that inhibit,suppress, and/or extinguish flames. "Flame(s)" is defined herein toinclude all oxidative, burning, and other combustion processes. Thecompositions of the present invention have effect against various typesof flames, however, the present compositions are particularly effectiveagainst conventional oxidative-type flames.

EXAMPLES

The invention is further defined by reference to the following examplesdescribing in detail the preparation of the compositions of the presentinvention. It will be apparent to those of ordinary skill in the artthat many modifications, both to materials and methods, may be practicedwithout departing from the purpose and intent of this invention. Allweights are in percentages unless otherwise noted.

Examples 1-39 Flame Suppression Compositions

A variety of flame suppression compositions, and the reaction productsgenerated by combusting the compositions, were prepared according to theinvention described herein and shown below in Table II. The compositionsprepared included the organic binder system and one or more of aninorganic halogen-containing component containing the specific halogensof the present invention. The temperatures indicated are the temperatureat which the flame suppression composition combusts to generate thereaction products for application to the flame.

    TABLE II       -                   Den        % % % % % % V % Temp. Mol Mol Mol Mol Mol Mol Mol Mol Mol lb/              # Binder KIO.sub.4 KBrO.sub.3 KI KBr NH.sub.4 IO liq °     C. KI KBr Hx H.sub.2 O COH.sub.2 O.sub.2 CO I.sub.2 OH K.sub.2 I     in.sup.3 FM       1 12 -- -- -- -- 70 27.5 490 -- -- 42 0.83 -- -- 0.290 -- -- 0.098 1.9       2 6.5 93.5 -- -- -- -- 22.8 1119 0.336 -- -- 0.35 -- 0.040 0.446 0.003       0.140 -- --       3 9.5H 90.5 -- -- -- -- 30.9 980 0.395 -- -- 0.32 0.518 -- 0.330 --     0.014 -- --       4 9.5 90.5 -- -- -- -- 27.0 1072 0.351 -- -- 0.40 -- 0.056 0.472 0.012       0.032 0.113 --       5 12 88 -- -- -- -- 32.4 1038 0.360 -- -- 0.45 0.217 -- 0.452 0.001     0.025 0.108 --       6 8.5 88 -- -- 3.5 -- 23.4 933 0.385 0.029 -- 0.35 -- 0.106 0.419 --     0.013 0.115 --       7 8.5 87 -- -- 4.5 -- 24.1 998 0.379 0.038 -- 0.35 -- 0.010 0.419 --     0.013 0.114 --       8 8.5 82 -- -- 9.5 -- 23.7 1019 0.349 0.079 -- 0.35 -- 0.063 0.419     0.001 0.016 0.112 --       9 8.5 75 -- -- 16.5 -- 23.2 1043 0.308 0.139 -- 0.3 -- 0.015 0.419     0.001 0.021 0.110 --       10 9.5 70 -- -- 21.5 -- 22.8 1049 0.291 0.180 -- 0.34 0.033 -- 0.386     -- 0.018 0.108 2.0       11 8.5 72.5 -- -- 19 -- 23.0 1051 0.295 0.160 -- 0.35 0.003 -- 0.414     -- 0.022 0.109 2.0       12 8.5 -- 72.5 -- 19 -- 20.8 1227 -- 0.579 -- 0.35 -- 0.139 0.417     0.015 -- 0.098 --       13 8.5 -- 65.5 -- 26 -- 19.9 1236 -- 0.609 -- 0.34 -- 0.077 0.419     0.014 -- 0.097 --       14 10 -- 59 -- 31 -- 23.5 1220 -- 0.603 -- 0.38 0.150 -- 0.387 0.010     -- 0.094 1.5       15 8 -- 59 -- 31* -- 19.2 1199 -- 0.612 -- 0.30 -- 0.046 0.421 0.025     -- 0.096 --       16 8 -- 59 -- 31** -- 19.3 1214 -- 0.670 -- 0.31 -- 0.039 0.423 0.033     -- 0.097 --       17 10 -- 57 -- 31* -- 23.3 1170 -- 0.602 0.001 0.36 0.184 -- 0.367     0.053 -- 0.093 1.5       18 8.1 -- 57 -- 33.5 -- 19.0 1199 -- 0.623 -- 0.30 -- .035 0.421 0.056       -- 0.096 --       19 9.1 -- 55 -- 33.9 -- 21.7 1203 -- 0.614 -- 0.40 0.084 -- 0.399     0.049 -- 0.095 1.5       20 9.1 -- 55 -- 17*** -- 20.6 1115 -- 0.468 -- 0.30 0.210 -- 0.447     0.061 -- 0.092 1.9       21 9.1 -- 22.5 -- 33.9* 22.5 21.1 1188 -- 0.599 -- 0.32 0.084 -- 0.408       0.038 -- 0.095 --       22 9.1 -- 44 -- 33.9 10 20.6 1115 -- 0.468 -- 0.30 0.210 -- 0.437     0.033 -- 0.092 1.1       23 9.6 -- -- -- -- 90.4 22.9 487 -- -- 0.330 0.81 0.455 -- 0.273 -- --       0.102 2.5       24 9.6 90.4 -- -- -- -- 25.9 954 0.406 -- -- 0.34 -- 0.146 0.432 0.005       0.011 0.115 --       25 9 50.4 -- 40.4 -- -- 22.7 828 0.477 -- -- 0.23 0.206 -- 0.287 --     0.002 0.108 --       26 9 55.6 -- 35.4 -- -- 22.9 939 0.462 -- -- 0.27 0.139 -- 0.271 --     0.006 0.109 --       27 9 58.6 -- 32.4 -- -- 23.0 988 0.450 -- -- 0.29 0.097 -- 0.327 0.001       0.009 0.109 --       28 9 65.6 -- 25.4 -- -- 23.3 1066 0.412 -- -- 0.32 -- -- 0.404 0.001     0.023 0.111 --       29 9 65 -- 26 -- -- 23.5 1062 0.416 -- -- 0.32 0.007 -- 0.398 0.003     0.022 0.111 --       30 9 65.5 -- 25.5 -- -- 23.3 1066 0.413 -- -- 0.40 0.001 -- 0.403 --     0.023 0.111 --       31 9 -- -- -- -- 81 18.6 498 -- -- 0.431 0.74 0.215 -- 0.385 -- --     0.103 2.0                  0.021       32 9 11 -- -- -- 80 21.5 484 0.067 -- 0.380 0.70 0.317 -- 0.369 -- --     0.102 2.1                  0.014       33 9 21 -- -- -- 70 22.3 696 0.069 -- 0.292 0.82 0.116 -- 0.381 -- --     0.106 --                  0.031       34 9 31 -- -- -- 60 22.6 795 0.138 -- 0.213 0.79 0.046 -- 0.386 --     0.002 0.107 --                  0.051       35 9 36 -- -- -- 55 22.7 841 0.162 -- 0.170 0.78 0.029 -- 0.391 --     0.003 0.108 --                  0.041       36 9 36 + -- -- -- 53 22.5 768 0.163 -- 0.146 0.77 0.037 -- 0.421 --     0.001 0.107 --         2LC       37 7.1 36 + -- -- -- 46 20.8 541 0.168 -- -- 0.71 0.040 -- 0.517 -- --       0.103 1.8         9.1lC       38 11 -- -- -- -- 51 + 39 20.0 871 0.085 0.174 -- 0.19 -- -- 0.635     0.964 -- -- 1.2             LiCO   I.sub.2       39 11 -- 12 -- -- 45 + 32 22.3 385 0.222 0.072 -- 0.28 0.036 -- 0.668     1.02 -- 0.087 1.0             LiCO.sub.2   0.011     *2% lithium carbonate was included in the composition to facilitate     hydrogen halide scavenging.     **Sodium oxalate coolant was included in the composition to facilitate     cooling.     ***Both scavenging agents and coolant were included in the composition.

The amount of various reaction products produced by the compositionsafter combusting for use as a flame suppressant is shown in various molefractions above. Moreover, several of the compositions have a figure ofmerit ("FM") that indicates a high potential effectiveness for flamesuppression. An FM of 1.0 is a 10 pound "unit" of HALON having a 288 in³volume.

Although preferred embodiments of the invention have been described inthe foregoing description, it will be understood that the invention isnot limited to the specific embodiments disclosed herein but is capableof numerous modifications by one of ordinary skill in the art. It willbe understood that the materials used and the chemical details may beslightly different or modified without departing from the methods andcompositions disclosed and taught by the present invention.

What is claimed is:
 1. A method of suppressing flames comprising:combining an inorganic halogen-containing component comprising bromine, iodine, or a mixture thereof, and an organic binder system having a heat of formation of less than about 200 cal/g to form a solid composition; generating a plurality of reaction products from the composition in a substantially gaseous form, wherein the reaction products have a velocity; and applying the reaction products at a temperature of between about 160° C. to 1200° C. to at least one flame in an amount sufficient to suppress the flame, wherein substantially all the halogen is solid after suppressing the flame.
 2. The method of claim 1, wherein the gaseous reaction products are generated by combusting the composition at a temperature of about 160° C. to 1200° C. prior to application to the at least one flame.
 3. The method of claim 1, which further comprises reducing the velocity of the gaseous reaction products generated from the composition to facilitate directing the reaction products into the flame.
 4. The method of claim 1, further comprising applying the reaction products in an amount sufficient to extinguish the flame.
 5. The method of claim 1, wherein the reaction products generated are selected to comprise H₂ O, CO, and a halogen-containing byproduct selected from the group consisting of KI, KBr, I₂ OH, K₂ I, and a mixture thereof.
 6. The method of claim 1, wherein the organic binder system is provided in an amount of about 4 to 15 weight percent of the composition.
 7. The method of claim 1, wherein the inorganic halogen-containing component is selected to comprise potassium bromide, potassium bromate, potassium iodide, potassium iodate, ammonium bromide, ammonium bromate, ammonium iodide, or ammonium iodate, or a mixture thereof.
 8. The method of claim 7, wherein the inorganic halogen-containing component is selected from the group consisting of potassium iodate, potassium bromate, potassium bromide, ammonium iodate, and a mixture thereof.
 9. The method of claim 1, wherein the organic binder system is prepared by combining:a binder resin of at least one curing binder, melt cast binder, solvated binder, or a mixture thereof; a curative present in about 1 to 3 weight percent; and a plasticizer present in about 10 to 30 weight percent, wherein the organic binder system has a heat of formation of less than about 0 cal/g.
 10. The method of claim 9, further comprising selecting the organic binder system to include at least one of an antioxidant, an opacifier, or a scavenger.
 11. The method of claim 9, wherein the binder resin is selected to comprise carboxy-terminated polybutadiene, polyethylene glycol, polypropylene glycol, hydroxy-terminated polybutadiene, polybutadiene acrylonitrile, polybutadiene acrylic acid, butacene, glycol azido adipate, polyglycol adipate, or a mixture thereof.
 12. The method of claim 1, wherein the organic binder system is provided in an amount of about 4 to 30 weight percent of the composition.
 13. The method of claim 12, wherein the organic binder system is provided in an amount of about 8 to 15 weight percent of the composition.
 14. The method of claim 12, wherein the organic binder system is provided in an amount of about 8 to 12 weight percent of the composition.
 15. A method of suppressing flames comprising:combining about 70 to 96 weight percent of an inorganic halogen-containing component comprising bromine, iodine, or a mixture thereof, and about 4 to 30 weight percent of an organic binder system having a heat of formation of less than about 200 cal/g to form a solid composition; generating a plurality of reaction products from the composition in a substantially gaseous form, wherein the reaction products have a velocity; and applying the reaction products at a temperature of between about 160° C. to 1200° C. to at least one flame in an amount sufficient to suppress the flame, wherein substantially all the halogen is solid after suppressing the flame.
 16. The method of claim 15, wherein the gaseous reaction products are generated by combusting the composition at a temperature of about 160° C. to 1200° C. prior to application to the flame.
 17. The method of claim 15, which further comprises reducing the velocity of the gaseous reaction products generated from the composition to facilitate directing the reaction products into the flame.
 18. The method of claim 5, further comprising applying the reaction products in an amount sufficient to extinguish the flame.
 19. The method of claim 15, wherein the reaction products generated are selected to comprise H₂ O, CO, and a halogen-containing byproduct selected from the group consisting of KI, KBr, I₂ OH, K₂ I, and a mixture thereof.
 20. The method of claim 15, wherein the inorganic halogen-containing component is selected to comprise potassium bromide, potassium bromate, potassium iodide, potassium iodate, ammonium bromide, ammonium bromate, ammonium iodide, or ammonium iodate, or a mixture thereof.
 21. The method of claim 20, wherein the inorganic halogen-containing component is selected from the group consisting of potassium iodate, potassium bromate, potassium bromide, ammonium iodate, and a mixture thereof.
 22. The method of claim 15, wherein the organic binder system is prepared by combining:a binder resin of at least one curing binder, melt cast binder, solvated binder, or a mixture thereof; a curative present in about 1 to 3 weight percent; and a plasticizer present in about 10 to 30 weight percent, wherein the organic binder system has a heat of formation of less than about 0 cal/g.
 23. The method of claim 22, further comprising selecting the organic binder system to include at least one of an antioxidant, an opacifier, or a scavenger.
 24. The method of claim 22, wherein the binder resin is selected to comprise carboxy-terminated polybutadiene, polyethylene glycol, polypropylene glycol, hydroxy-terminated polybutadiene, polybutadiene acrylonitrile, polybutadiene acrylic acid, butacene, glycol azido adipate, polyglycol adipate, or a mixture thereof. 